vcap_dev_setup_centos6

port cloudfoundry/vcap/dev_setup to CentOS6

• change bin/vcap_dev_setup to use root privileges and yum command.
• change cookbooks to use chef on CentOS6.
• add proxy env support to maven install in uaa cookbook.

TODO

• PostgreSQL cookbook haven't been changed now.
• php cookbook haven't been changed now.
• echo cookbook haven't been changed now.
• filesystem cookbook haven't been changed now.

BUGS

• If build vcap by rvm, the rubygems env may be wrong when your install ruby and start~